Composition for increasing plant productivity protein nitrogen level and anion uptake, possessing kinetin-supplementing, cytokinin-like and membrane activities

ABSTRACT

The invention relates to new compositions which contain 0.5 to 90% by weight of a phthalazine derivative having the general formula (I), ##STR1## wherein R 1  stands for hydrogen, halogen, a straight-chained or branched C 1-4  alkyl group having optionally a chlorine or hydroxy substituent, a C 2-4  alkenyl group, or an optionally alkyl-substituted amino, sulfhydryl or hydroxy group, and 
     B 1  and B 2 , which may be identical or different, have no meaning or stand for guanidine and/or hydrazine base, 
     and/or an imidazole derivative of the general formula (II), ##STR2## wherein n is equal to zero or 4, 
     R 2  stands for hydrogen, a straight-chained or branched C 1-5  alkyl group having optionally a chlorine or hydroxy substituent, or a C 2-5  alkenyl group, 
     X stands for an organic or inorganic anion, and 
     in the compounds of the general formula (II) wherein n is equal to 4 R 1  has the same meanings as defined above, together with 10 to 95% by weight of one or more solid and/or liquid carrier(s) and 1 to 10% by weight of one or more surfactant(s). 
     The new compositions according to the invention increase the productivity, protein nitrogen level and anion uptake of plants, furthermore they also possess kinetin-supplementing, cytokinin-like and membrane activities. The new compositions can be applied to advantage for increasing crop yield and the nutrient value of the crop.

The invention relates to new compositions for increasing plant productivity, protein nitrogen level and anion uptake, which also possess kinetin-supplementing, cytokinin-like and membrane activities.

The compositions according to the invention contain 0.5 to 90% by weight of a phthalazine derivative having the formula (I). ##STR3## wherein R₁ is hydrogen, halogen, a straight-chain or branched C₁₋₄ alkyl group having optionally a chlorine or hydroxy substituent, a C₂₋₄ alkenyl group, or an optionally alkyl-substituted amino, sulfhydryl or hydroxy group, and

B₁ and B₂, which may be identical or different, have no meaning or stand for guanidine and/or hydrazine base, and/or an imidazole derivative of the formula (II), ##STR4## wherein n is equal to zero or 4,

R₂ stands for hydrogen, a straight-chained or branched C₁₋₅ alkyl group having optionally a chlorine or hydroxy substituent, or a C₂₋₅ alkenyl group,

X stands for an organic or inorganic anion, preferably chloride or bromide ion, and

in the compounds of the formula (II) wherein n is equal to 4 R₁ has the same meanings as defined above, together with 10 to 95% by weight of one or more solid and/or liquid carrier(s) and 1 to 10% by weight of one or more surfactant(s).

Beside fertilizers and pesticides, chemicals which have been used for a long time in plant cultivation, the use of substances which influence the growth and crop yield of plants has become increasingly widespread in the last decades. These latter substances are generally referred to as regulators.

Most of the regulators are natural or synthetic hormones capable of influencing or regulating various processes of plant development [Kolcsei, M., Nadasy, M.: Magyar Kemikusok Lapja XXXIV, No. 3, pp. 122-126 (1979) (in Hungarian)].

The natural and synthetic auxines, which are indole-acetic acid derivatives, exert multiple influences on the vital processes of plants. The synthetic auxines can be classified into four main groups, i.e. indole derivatives, naphthyl derivatives, phenoxy derivatives and benzoic acid derivatives. The most widespread representatives of these substances are methyl naphthylacetate, which is applied as a dusting composition for inhibiting the sprouting of potato, and potassium naphthylacetate which is utilized to promote the rooting of cuttings and to inhibit premature fruit fall.

Gibberellines, which form a further main group of regulators, are capable of and utilized in practice for stimulating plant growth, inducing flowering and resolving the repose period.

Cytokinins, which form the third main group of regulators, influence the biological processes of plants from many sides. They promote cell division, retard senescence processes, suspend dominance and resolve the repose period. Of the natural cytokinins zeatin and lupin are known, they do not have, however, wide practical utilization.

The fourth main group of regulators encompasses the abscissins, which participate in the endogeneous regulation of senescence and also possess growth inhibiting and organ abscission promoting effects. Although more than 70 types of compounds with a xanthonine skeleton, possessing abscissic acid-like effects, have been synthetized so far, they have had no practical utilization.

Ethylene, a substance which forms in great amounts during the ripening process of fruits and accelerates the ripening process, is the only gaseous hormone. For the same purpose 2-chloroethylphosphonic acid is utilized in practice.

Beside plant hormones [auxines, gibberellines, cytokinins, plant growth retardants (PGR), abscissins, ethylene, etc.] various other compounds with biological activities have also been utilized in agrochemistry. Thus e.g. 2-chloroethyltrimethyl-ammonium chloride (CCC), a substance belonging to the PGR group, is widely used to increase the crop yield of wheat and barley (U.S. Pat. No. 3,156,544). The endogeneous cytokinins (zeatine, lupin) and the synthetic cytokinins (kinetin, benzyladenine, etc.) also increase significantly the crop and protein yield. The synthesis of these substances is, however, very expensive, which strongly inhibits their agrotechnical utilization [Skoog, F., Strong, F. M., Miller, C. O.: Science 148, pp. 532-533 (1965)].

The Hungarian patent specification No. 162,937 describes 2-chloroethane-(thiono)-phosphonic acid amide derivatives as substances for promoting germination, stimulating the development of shoots and accelerating ripening.

The Hungarian patent specification No. 163,510 discloses compositions containing thiourea derivatives, which promote the abscission of fruits. The Hungarian patent specification No. 164,190 teaches that certain haloethanesulfinic acids, such as 2-chloroethanesulfinic acid bromide, accelerate ripening, delay senescence and inhibit the growth of plants.

It is disclosed in the Hungarian patent specification No. 164,512 that if plant seeds are treated prior to sowing with a bis(dimethyl-ammonium)-p-chlorobenzyl phosphate derivative, the grain yield and nitrogen uptake increase.

The Hungarian patent specifications Nos. 164,587 and 164,866 disclose that β-haloethyl silanes, like ethylene, accelerate ripening.

According to the Hungarian patent specification No. 164,885 certain pyrimidine derivatives, such as 2-methylthio-4-ethylamino-5-nitro-6-methylamino-pyrimidine, and salts thereof possess germination inhibiting effects and also inhibit longitudinal cell growth.

The Hungarian patent specification No. 167,576 describes s-triazine-dione derivatives for influencing the flowering and gamogenesis of plants. Compositions containing allophane imidates, which also influence plant flowering and gamogenesis, are disclosed in the Hungarian patent specification No. 168,916.

According to the Hungarian patent specification No. 170,761 certain phthalimide derivatives, such as 3-trichloromethyl-phthalamide and 1-(3-chloro-phthalimido)-cyclohexylcarboxamide, accelerate the emergence and growth of plants.

Compositions for increasing the sugar content of plants, containing 2-(aminoalkoxy)-4-phenyl-thiazole derivatives or 2,4-bis(N'-methyl-4'-pyridilium)-s-triazole diiodide, are described in the Hungarian patent specifications Nos. 162,520 and 165,576, respectively.

The Hungarian patent specification No. 165,576 describes compositions containing gibberelline plus an imidazole derivative, and fungicides plus certain herbicidal agents in very low concentrations, which accelerate the growth of sugar beet leaves. These compositions have not, however, been utilized in practice.

The endogeneous (zeatin, lupin) and synthetic (kinetin, benzyladenine, etc.) forms of cytokinins are all 6-amino-purine derivatives, the main biological effect of which is the acceleration of the mitosis frequency [Strong, F. M.: Topics in microbial chemistry, Wiley, New York (1958); Skoog, F., Strong, F. M., Miller, C. O.: Science 148, pp. 532-533 (1965)]. Beside this main effect, cytokinins proved to possess various other side effects as well, which can be utilized to advantage for plant cultivation, horticultural and microbiological purposes. Thus

(a) they promote the fresh and dry weight gain of callus and mericlone cultures,

(b) they lead to a more favorable accumulation of organic substances in the vegetative and generative organs,

(c) they promote chlorophyll preservation and increase of its photochemical activity,

(d) they promote the rejuvenation of leaf tissue, which results in the retardation of senescence,

(e) they increase the intensity of the photosynthetic fixation of carbon dioxide,

(f) they increase the photolytic activity which can be measured by the decomposition of HTO,

(g) they increase the intensity of the amino acid and protein synthesis, particularly by increasing significantly the absolute and relative amounts of protein nitrogen fraction soluble in 0.5% sodium chloride solution, and

(h) they increase the intensity of nucleic acid synthesis.

Up to now, however, only laboratory scale methods have been described for the synthesis of adenine base and specific derivatives thereof. Due to the high expenses of their production the promising effects mentioned above could not be utilized in plant cultivation, horticulture and microbiology. Thus, in spite of the fact that a vast number of compositions with PGR-effects were reported, no cytokinin-like composition was applied in the practice of agriculture, particularly not under large-scale conditions. The known compositions with PGR effects do not possess the characteristic main effect of cytokinins, thus they cannot exert cytokinin-like activity. This is the reason why no composition with cytokinin-like effects can be found on the market.

In our research work directed to increased plant growth, productivity, protein level and crop yield it has been found that the compositions according to the invention, which contain 0.5 to 90% by weight of a phthalazine derivative of the formula (I) and/or an imidazole derivative of the general formula (II), together with 10 to 95% by weight of one or more liquid and/or solid carrier(s) and 1 to 10% by weight of one or more surfactant(s), can be applied to advantage and with very favorable results in influencing certain plant physiological processes.

Where compositions including both a phthalazine derivative and an imidazole derivative are employed, it is preferred that said compositions contain 0.5 to 90% by weight of a 4:1-1:4 mixture of the phthalazine of the formula (I) and the imidazole of the formula (II), together with 10 to 90% by weight of one or more solid carriers, preferably amorphous silicic acid, or a ground mineral, and 1 to 15% by weight of one or more surfactants, preferably a mixture of an anionic and a nonionic tenzide.

A more preferred feature of the invention includes compositions containing 0.5 to 70% by weight of a 1:4-4:1 mixture of a phthalazine derivative of the formula (I) and an imidazole derivative of the formula (II), together with 30 to 80% by weight of one or more liquid diluents, preferably a nonphytotoxic oil, and 1 to 20% by weight of one or more solid carriers, preferably active silicic acid, and 1 to 15% by weight of one or more surfactants, preferably a mixture of an anionic and a nonionic tenzide.

Some phthalazine derivatives having the formula (I) have already been described in the literature [Curtius, Hoesch: J. prakt. Chem. 76, 2, 301 (1908); Draw. Hatt: J. Chem. Soc. 1, 16 (1937); Stanly, Parker: J. Am. Chem. Soc. 56, 241 (1934); Barber, Wrogg: J. Chem. Soc. 6, 1458 (1948)]. These references did not give, however, any information about the effects of these compounds exerted on protein level, photosynthesis and plant productivity.

It is known that 1,4-dihydroxyphthalazine occurs in three tautomeric forms; therefore the compounds of the formula (I) have been drawn in three different forms (a, b and c, respectively). The term "a compound of the formula (I)" encompasses all the possible isomers and isomeric mixtures of the respective phthalazine derivatives.

According to the U.S. Pat. No. 2,654,689 1,4-dihydroxyphthalazine and metal salts thereof possess fungicidal effects.

Some of the imidazole derivatives having the formula (II) have also been described in the literature [Auwers, Mauss: Chem. Ber. 61, 2414 (1928); Davies, Mamalis, Petrow, Sturgeon: J. Pharm. Pharmacol. 3, 420 (1951); Weidenhagen, Train, Wagner, Nordstrom: Chem. Ber. 75, 1936 (1942); Pozharsky, Simonov: Zh. Obsch. Khim. 33, 179 (1963)]. The effects of these compounds exerted on protein level, photosynthesis and plant productivity were, however, unknown till now.

It has been observed that the compositions according to the invention, which contain a phthalazine derivative of the formula (I) and/or an imidazole derivative of the formula (II) together with one or more liquid and/or solid carrier(s) or diluent(s) and surfactant(s), can be applied to influence favourably the physiological processes on a wide variety of cultivated plants, and exert their beneficial effects in relatively low concentrations (1 to 200 ppm or 0.5 kg of active agent/hectare).

It has also been observed that the compositions which contain phthalazine derivatives of the formula (I) exert more significant effects on plant productivity, protein synthesis and photosynthesis than the compositions described in the Hungarian patent specification No. 170,761, which latter contain as active agent phthalimide derivatives, i.e. compounds with closely related chemical structures. These known compositions exert just the opposite regulating effects, furthermore they influence only plant growth (more particularly, plant height), but do not act on the protein level and photosynthesis.

It has also been observed that the imidazole derivatives of the formula (II) which, unlike cytokinins, can be synthesized by inexpensive methods so that their agricultural utilization is economic, possess not only cytokinin-like cell-biological effects, but have membrane activity (i.e. promote the anion uptake), as well, which does not appear to be the case with the endogeneous and synthetic cytokinins.

It has also been observed, surprisingly, that while the new compositions increase the organic substance production almost aspecifically on almost all of the plant varieties examined, the extent of protein synthesis- and photosynthesis-stimulating effect already depends on the type of the plant treated.

We have also elaborated and applied well-reproducible methods to examine the biological effects of the compositions according to the invention and to test how they influence the various vital processes of plants. The effects exerted on protein synthesis were examined by isotope technique, measuring the incorporation of labelled amino acids [glycine-1-¹⁴ C, glycine-2-¹⁴ C and methionine-(S-methyl-¹⁴ C), respectively]. The promotion of photosynthesis was also examined by isotope technique, measuring the incorporation of labelled carbon dioxide (¹⁴ CO₂). The effects exerted on nutrient uptake were tested by measuring the incorporation of labelled phosphate ions, whereas the inhibiting effect exerted on the decomposition of chlorophyll was tested by measuring the extinction of the methanol extracts as 665 mμ.

The results of the laboratory tests were in complete agreement with the results observed when treating the plants under field conditions.

Based on the test results, the compositions of the invention exert the following effects on the vital processes of plants:

(a) the internodium development shortens, e.g. for vines, the number and dry weight of leaves increases, and the carbon/nitrogen ratio decreases favorably;

(b) owing to the promotion of root development (root factor) the growth of overground (aerial) shoots becomes more intense, whereupon the period of vegetative development shortens (e.g. by 6 weeks for brewer's barley) and the development of generative organs increases, which involves the increase of crop yield;

(c) in perennial papilionaceae (e.g. in alfalfa cultures) and in pasturage cultures (e.g. maize for silage, grass) the uptake of soil nitrogen and phosphorous increases, thus the protein nitrogen content of the leaves increases considerably and the carbon/nitrogen ratio decreases;

(d) when soybean, maize, brewer's barley, wheat, etc. are treated with a composition according to the invention, the total nitrogen content of the grain crop increases by about 20%, coupled with an even higher increase in protein nitrogen content;

(e) when sugar beet is treated with a composition according to the invention, the crop yield and the polarimetrically measurable sugar content increase, which involve an increase in sugar yield attainable on unit area; furthermore the plants reach their genetically determined maximum sugar content within a shorter period, thus they can be harvested earlier;

(f) when vines are treated with a composition according to the invention prior to flowering and then twice more until ripening, the average weight of the clusters, the thousand-berry weight and the sugar content determined by refractometry increase;

(g) treatments with a composition according to the invention considerably accelerate the rooting of vine and fruit-tree graft, the differentiation of stock and sprouts and ripening, which also have a favorable influence on the maturation and frost resistance of the stock;

(h) owing to the fact that the compositions according to the invention increase the frequency of mitosis, they can be applied to advantage in plant tissue cultivation to effect tissue and organ differentiation of the callus;

(i) the phytotoxic effects exerted on cultivated plants by various herbicides can be counterbalanced or corrected, when the plants are sprayed with a composition according to the invention in order to avoid their damaging.

The cultivated plants can be treated with the compositions according to the invention prior to sowing or planting, or treatment can be performed after sowing or planting by spraying the composition onto the soil. The plants can also be treated with the compositions according to the invention at one or more pre-determined stage of their development. The timing of treatment depends on the development stage and property of the plant to be influenced. In the majority of the cases appropriate influencing effects can be achieved even upon a single treatment, in some instances, however, multiple treatments are preferred (e.g. on vines).

The dose of the treatment varies, depending on the actual composition of the preparation, generally between 0.5 and 20 kg/ha; in most instances, however, even a very low dose (e.g. 0.5 to 2 kg/ha) is sufficient to attain the desired result. The preparations according to the invention do not exert any phytotoxic effect on cultivated plants even when applied in very high dose (e.g. 20 to 30 kg/ha). As a further advantage, the compositions according to the invention are completely free to skin irritating, skin sensitizing (allergenic) and eye irritating effects, and they are practically non-toxic (LD₅₀ : 2500 mg/kg).

The use of the compositions according to the invention in various fields of agriculture (plant cultivation) is described in detail in the examples.

The phthalazine derivatives of the formula (I) can be prepared in a manner known per se in that the appropriately substituted phthalic acid or a reactive derivative thereof (e.g. its anhydride, chloride, ester, etc.) is reacted with an excess of hydrazine or hydrazine sulfate at 90° to 160° C. in a solvent medium. As a general rule, the increase of the hydrazine excess, the temperature and the reaction time favor the formation of the dihydroxyphthalazine compound. Depending on the reaction conditions, a monohydrazide derivative of the formula (III), ##STR5## a dihydrazide derivative of the formula (IV), ##STR6## an N-aminophthalimide of the formula (V), ##STR7## and/or a mixed amide-hydrazide compound of the formula (VI) ##STR8## can be formed. The resulting mono-and dihydrazides, as well as the mixed amide-hydrazide compound undergo ring closure upon heating to form a dihydroxyphthalazine.

The resulting dihydroxyphthalazine derivative can be reacted then with hydrazine or guanidine base in a solvent medium to obtain a salt-like compound. The resulting substance is separated by filtration, washed and dried.

The imidazolium derivatives of the formula (II) can be prepared in a manner known per se in that the appropriately substituted imidazole is reacted with an alkyl halide or alkyl chloroformate at 50° to 160° C. in an organic solvent medium (e.g. acetone, benzene, toluene, etc). The resulting substituted imidazolium salt is separated by filtration, washed and dried. Depending on the reaction conditions, the resulting product may contain a minor amount of the respective dialkylated derivative as impurity. The amount of this dialkylated substance is, however, so small that it does not influence the effect of the composition.

If a pure product, free of dialkylated by-products, is to be obtained, the reaction is performed in two separate steps, i.e. the N-alkyl-imidazole is prepared first, and then it is converted into the respective imidazolium salt (e.g. halide, sulfate, etc.) in a separate step.

The preparation of the active agents [phthalazine derivatives of the formula (I) and imidazolium derivatives of the formula (II)] is described in the following Examples.

EXAMPLE 1

148.2 g (1 mole) of phthalic acid anhydride and 130 g (1 mole) of hydrazine sulfate are introduced into a 1500 ml flask equipped with a thermometer, a stirrer and a reflux condenser. Thereafter a solution of 90 g of sodium hydroxide in 800 ml of water is added to the mixture at 40° C., and the mixture is heated to boiling under constant stirring. The mixture is refluxed for one hour, thereafter it is cooled to 60° C., and its pH is adjusted to 5 to 6 with 50 ml of concentrated hydrochloric acid. The resulting mixture is stirred at 20° to 40° C. for 4 hours. The spearated solids are filtered off and dried at 80° to 100° C.

448 g (4 moles) of guanidine nitrate are introduced into a 2500 ml flask, the salt is suspended in 800 ml of ethanol, and then a solution of 224 g (4 moles) of potassium hydroxide in 500 ml of ethanol is added. After 0.5 hours of stirring the solution is filtered, and the filtrate is added to the solid dihydroxyphthalazine obtained in the first step. The resulting mixture is stirred at room temperature for one hour, then the separated white, crystalline substance is filtered off, washed and dried at 60° C.

219.4 g (0.86 moles, 86.3%) of dihydroxyphthalazine diguanidine salt are obtained. The white, microcrystalline substance melts at 280° C.

EXAMPLE 2

118.2 g (1 mole) of benzimidazole are introduced into 2000 ml flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel, and the solid is dissolved in 800 ml of toluene. 200 ml of isopropyl chloroformate are added to the stirred solution, under maintaining the temperature of the mixture at 20° C. When the addition is complete, the mixture is warmed to 60° C. and stirred for 2 hours at this temperature. The mixture is stirred then at 90° to 100° C. for additional two hours, finally it is cooled to 15° to 20° C. The separated greyish-white crystalline substance is filtered off, washed and dried at 80° C. 125.5 g (81.7%) of a substance melting at 134°-136° C. are obtained.

Similarly other phthalazine derivatives of the formula (I) and the other alkylimidazole derivatives of the formula (II) can be prepared.

The compositions according to the invention can be prepared as described in the following Examples.

EXAMPLE 3

65 g of 1,4-dihydroxyphthalazine diguanidine salt (technical quality; purity grade: 92%), 5 g of Ultrasyl VN-3 (filling agent), 20 g of Emulsogen M (emulsifying agent) and 111 g of vaseline oil (technical quality) are introduced into a laboratory ball mill. 400 g of glass beads, 1.5 mm in diameter, are added, and the mixture is milled for 1.5 hours at a rate of 775 r.p.m. The glass beads are separated from the mixture by sieving through a metal sieve with a gap size of 1 mm.

The resulting oily composition, containing 30% by weight of 1,4-dihydroxyphthalazine diguanidine salt, is emulsified in water to form a 1 w/w % emulsion. This emulsion is stable and free from sediments after 12 hours of standing. After 24 hours of standing a sediment separates from the emulsion, which can be emulsified reversibly upon gentle shaking.

EXAMPLE 4

48 g of N-isopropyl-benzimidazolium chloride (technical quality; purity grade: 94%), 4 g of Ultrasyl VN-3 (filling agent), 20 g Emulsogen M (emulsifying agent) and 128 g of vaseline oil (technical quality) are introduced into a laboratory ball mill. 400 g of glass beads, 1.5 mm in diameter, are added, and the mixture is milled for one hour at a rate of 775 r.p.m. The glass beads are separated from the mixture by sieving through a sieve with a gap size of 1 mm.

The resulting oily composition, containing 20% by weight of N-isopropyl-benzimidazolium chloride, is diluted with water to an active agent content of 1% by weight. This emulsion is stable and free from sediments after standing for 12 hours.

EXAMPLE 5

22 g of 1,4-dihydroxyphthalazine diguanidine salt (technical quality; purity grade: 92%), 4 g of Ultrasyl VN-3 (filling agent), 20 g of Emulsogen M (emulsifying agent) and 117 g of vaseline oil (technical quality) are introduced into a laboratory ball mill. 400 g of glass beads, 1.5 mm in diameter, are added, and the mixture is milled for 2 hours at a rate of 775 r.p.m. The glass beads are separated from the mixture by sieving through a sieve with a gap size of 1 mm. The resulting oily composition, containing 10% by weight of 1,4-dihydroxyphthalazine diguanidine salt, is diluted with water to an active agent content of 1% by weight. This emulsion is stable and free from sediments after standing for 12 hours.

EXAMPLE 6

22 g of 1,4-dihydroxyphthalazine diguanidine salt (technical quality; purity grade: 92%), 20 g of N-isopropylbenzimidazolium chloride (technical quality; purity grade: 96%). 4 g of Ultrasyl VN-3 (filling agent), 20 g of Emulsogen M (emulsifying agent) and 134 g of vaseline oil (technical quality) are introduced into a laboratory ball mill. 400 g of glass beads, 1.5 mm in diameter, are added, and the mixture is milled for 2.5 hours at a rate of 775 r.p.m. The glass beads are separated from the mixture by sieving through metal sieve witha gap size of 1 mm.

The resulting oily composition is diluted to twentyfold volume with water to obtain an emulsion stable for 12 hours.

EXAMPLE 17

11 g of N-isopropyl-benzimidazolium chloride (technical quality; purity grade: 96%), 4 g of Ultrasyl VN-3 (filling agent), 16 g of Emulsogen M (emulsifying agent) and 170 g of vaseline oil (technical quality) are introduced into a laboratory ball mill. 400 g of glass beads, 1.5 mm in diameter, are added, and the mixture is milled for one hour at a rate of 775 r.p.m. The glass beads are separated from the mixture by sieving through a metal sieve with a gap size of 1 mm.

The resulting composition is diluted to tenfold volume with water to obtain an emulsion stable for 12 hours.

EXAMPLE 8

52 g of 1,4-dihydroxyphthalazine diguanidine salt, g of Zeolex-444 (solid carrier), 6 g of powdery sulfite waste liquor, 3 g of Supermittel-1494 (dispersing agent), 1 g of Netzer IS (Wetting agent) and 0.2 g of Tensia defoamer (antifoaming agent) are introduced into a laboratory powder mixer. The mixture is homogenized, and then milled on an "Alpine 100 LU" type laboratory ultraplex mill.

The resulting composition, containing 50% of active agent, is diluted with water to form a 0.5% suspension. The floatability of the solids is 84-87% after 0.5 hours of standing, the wet sieve residue (examined on a DIN 100 sieve) is 1-1.5%.

EXAMPLE 9

91 g of technical 1,4-dihydroxyphthalazine diguanidine salt, 4 g of talc, 4 g of powdery sulfite waste liquor, 1 g of Netzer IS (wetting agent) and 0.2 g of methylene blue (dyestuff) are introduced into a laboratory powder mixer. The mixture is homogenized, and then milled on an Alpine 100 LU type laboratory ultraplex mill.

The wet sieve residue of the composition (examined on a DIN 100 sieve) is 3-4%.

EXAMPLE 10

53 g of N-isopropyl-benzimidazolium chloride, 37 g of Zeolex-444 (solid carrier), 5 g of powdery sulfite waste liquor, 3.5 g of Supermittel-1494 (dispersing agent), 1.5 g of Netzer IS (wetting agent) and 0.3 g of Tensia defoamer (antifoaming agent) are introduced into a laboratory powder mixer. The mixture is homogenized and then milled on an Alpine 100 LU type laboratory ultraplex mill.

The resulting composition, containing 50% of active agent, is diluted with water to form a 0.5% suspension. The floatability of the solids is 86-90% after 0.5 hours of standing; the wet sieve residue (examined on a DIN 100 sieve) is 0.5-1.5%.

EXAMPLE 11

84.2 g of N-isopropyl-benzimidazolium chloride, 9.5 g of talc, 5 g of powdery sulfite waste liquor, 1 g of Netzer IS (wetting agent) and 0.3 g of methylene blue (dyestuff) are introduced into a laboratory powder mixer. The mixture is homogenized and then milled on an Alpine 100 LU type laboratory ultraplex mill.

The wet sieve residue of the resulting composition (examined on a DIN 100 sieve) is 2-4%.

EXAMPLE 12

44.5 g of technical 1,4-dihydroxyphthalazine diguanidine salt, 42 g of N-isopropyl-benzimidazolium chloride, 9.5 g of talc, 5 g of powdery sulfate waste liquor, 1 g of Netzer IS (wetting agent) and 0.4 g of methylene blue (dyestuff) are introduced into a laboratory powder mixer. The mixture is homogenized, and then milled on an Alpine 100 LU type laboratory ultraplex mill. The wet sieve residue of the resulting composition (examined on a DIN 100 sieve) is 3-5%.

The plant growth regulating compositions according to the invention can be presented as a solid formulations (powder mixtures, granulates, etc.). In this instance e.g. kaolin, bentonite, active silicic acid, gypsum, calcium carbonate or talc can be applied as solid carrier or filling agent.

The compositions can also be presented as liquid formulations, of which the oily formulations are the most preferred, since they can be sprayed out easily at any stage of the development of the plant. Of the liquid diluents usable to produce oily formulations e.g. vaseline oil, fruit tree oils, other vegetable oils and non-phytotoxic mineral oil derivatives are to be mentioned.

Both the solid and the liquid formulations must contain surfactants, which may be cationic, anionic and nonionic tenzides and mixtures thereof. As cationic tenzides e.g. quaternary ammonium compounds (such as cetyl-trimethylammonium chloride), as anionic tenzides e.g. salts of dodecyl-benzenesulfonic acid, whereas as nonionic tenzides e.g. polyoxyethylene-alkylphenols, polyoxyethylene-sorbitanes, polyoxyethylene-triglycerides etc. can be applied. The anionic and nonionic tensides can also be utilized as mixtures.

The plant biological effects of the compositions according to the invention, as well as their use in plant cultivation are demonstrated by the following non-limiting Examples.

EXAMPLE 13 Effect on the daily growth of tobacco callus

The compositions according to the invention were diluted with water to an active agent content of 10 ppm, and then were added to the culture media prior to incubation. An untreated culture medium served as control. Tobacco callus was grown on the treated and untreated culture media (incubation period: 3 weeks), and the daily growth, the increase in cell number and the frequency of mitosis were measured according to the method of Skoog. The results of the test are summarized in Table 1.

                  TABLE 1                                                          ______________________________________                                                                        Cell                                                                  Daily    number/                                                                               Frequency                                Test                  growth,  g. 10.sup.4                                                                           of mitosis                               No.  Treatment        mg       units  %                                        ______________________________________                                         1    Untreated control                                                                               16.0     227.7  100                                      2    1,4-Dihydroxyphthalazine                                                                        19.3     266.0  117                                           diguanidine salt                                                          3    N--(n-Propyl)-benzimida-                                                                        22.8     327.5  143                                           zolium bromide                                                            4    1:1 mixture of the                                                                              24.1     375.2  165                                           active agents used in                                                          Tests 2 and 3                                                             ______________________________________                                    

The date demonstrate clearly that the treatment with the composition according to the invention resulted in an increase of the daily growth and cell number. The frequency of mitosis increased by 17-65%.

EXAMPLE 14 Effect on the growth of tobacco callus

The test described in Example 13 was repeated so that a culture medium containing 1 ppm of kinetin was used as control, and the compositions according to the invention were applied in amounts corresponding to 2 ppm of active agent. The results are listed in Table 2.

                  TABLE 2                                                          ______________________________________                                                              Dry weight                                                Test                 of the callus                                                                             Speed of growth                                No.  Treatment       mg         Index %                                        ______________________________________                                         1    Kinetin         174.11      97.17                                                                               100                                      2    1,4-Dihydroxyphthala-                                                                          170.92      98.23                                                                                98.16                                        zine diguanidine salt                                                     3    N--(n-Propyl)-benzimid-                                                                        194.09     116.89                                                                               119.0                                         azolium chloride                                                          4    1:1 mixture of the                                                                             198.21     119.37                                                                               121.52                                        active agents used in                                                          Tests 2 and 3                                                             ______________________________________                                    

EXAMPLE 15 Effect on the growth of callus isolated from Datura innoxia Mill. roots

The tests described in Examples 13 and 14 were repeated so that a culture medium containing 2 ppm of kinetin was used as control. The results are summarized in Table 3.

                                      TABLE 3                                      __________________________________________________________________________                 Fresh                                                                              Dry                                                                        weight                                                                             weight                                                                     of the                                                                             of the   Growth Speed of                                       Test        callus                                                                             callus                                                                             Dry sub-                                                                            Fresh                                                                              Dry                                                                               growth                                         No. Treatment                                                                              g   mg  stance %                                                                            weight mg/day                                         __________________________________________________________________________     1   Control with                                                                           4.9694                                                                             175.06                                                                             3.52 15.56                                                                              15.56                                                                             98.28                                              kinetin                                                                    2   1,4-Dihydroxy-                                                                         7.6110                                                                             269.07                                                                             3.53 24.37                                                                              24.46                                                                             149.20                                             phthalazine                                                                    diguanidine                                                                    salt                                                                       3   N--(n-Propyl)-                                                                         6.5772                                                                             209.13                                                                             3.17 20.92                                                                              18.78                                                                             128.10                                             benzimidazoli-                                                                 um bromide                                                                 4   Control with-                                                                          0.3968                                                                             28.08                                                                              7.07 0.32                                                                               1.65                                                                              1.97                                               out kinetin                                                                5   1,4-Dihydroxy-                                                                         0.9258                                                                             66.11                                                                              7.14 2.08                                                                               5.25                                                                              12.77                                              phthalazine                                                                    diguanidine                                                                    salt                                                                       6   N--(n-Propyl)-                                                                         0.6120                                                                             43.29                                                                              7.07 1.04                                                                               3.09                                                                              6.36                                               benzimidazo-                                                                   lium bromide                                                               __________________________________________________________________________

The percentage growth promoting effects of the compositions according to the invention, determined in the presence and in the absence of kinetin, are listed in Table 4.

                  TABLE 4                                                          ______________________________________                                                                   With    Without                                      No.    Treatment          kinetin kinetin                                      ______________________________________                                         1      Control            100     100                                          2      1,4-Dihydroxyphthalazine                                                                          156     648                                                 diguanidine salt                                                        3      N--(n-Propyl)-benzimidazo-                                                                        134     322                                                 lium bromide                                                            ______________________________________                                    

EXAMPLE 16 Inhibition of the decomposition of chlorophyll in barley, soybean, bean, alfalfa and maize

The active agent to be tested was dissolved in distilled water to form a 200 ppm solution, and leaf segments of the plants under examination, weighing 200 mg, were floated on the surface of the solution for 4 days in the dark. Thereafter chlorphyll was extracted from the leaf segments with methanol.

To determine the starting state, chlorophyll was extracted with methanol from untreated leaf segments weighing 200 mg. In the control test the leaf segments, weighing 200 mg, were floated on the surface of distilled water for 4 days in the dark, and then chlorophyll was extracted from the leaf segments with methanol.

The chlorophyll concentration was determined by measuring the extinction of the extracts at 665 mμ. The results are summarized in Tables 5 and 6.

                  TABLE 5                                                          ______________________________________                                                 Un-   Treatments                                                                     treated 1,4-Dihydroxy-                                                                           Diguanidine                                    Test          con-    phthalazine                                                                              salt     Promo-                                No.  Plant    trols   Chlorophyll, mg  tion, %                                 ______________________________________                                         1    Barley   3.7     --        9.7      162                                   2    Soybean  3.5     4.2       --       20                                    3    Soybean  3.5     --        5.4      54                                    4    Bean     4.2     5.8       --       38                                    5    Bean     4.2     --        6.5      54                                    ______________________________________                                    

                  TABLE 6                                                          ______________________________________                                         N--Alkyl-benzimid-                                                                              Alfalfa     Maize                                             azolium bromide  Chloro-  Pro-   Chloro-                                                                               Pro-                                   of the general   phyll    mo-    phyll  mo-                                    formula (II) used                                                                               content  tion   content                                                                               tion                                   in the treatment mg       %      mg     %                                      ______________________________________                                         1    N--methyl compound                                                                             0.83     6.4  0.80   23.0                                 2    N--ethyl compound                                                                              0.85     8.9  0.79   21.5                                 3    N--bromoethyl   0.64     --   0.71    9.2                                      compound                                                                  4    N--(n-propyl) compound                                                                         0.96     23.0 0.82   26.1                                 5    N--(n-butyl) compound                                                                          0.81     3.8  0.76   16.9                                 6    Untreated control                                                                              0.78     --   0.65   --                                   ______________________________________                                    

For alfalfa and maize the chlorphyll contents of 100 mg of green plant were examined.

The test results demonstrate clearly that the compositions according to the invention effectively inhibit the decomposition of chlorophyll.

EXAMPLE 17 Effect on the preservation of chlorophyll

The effects of cytokinin-like regulators on the preservation of chlorophyll are summarized in Table 7. Endogeneous and synthetic cytokinins were applied as comparative substances. Solutions with varying concentrations, but always more dilute than 10⁻⁴ moles, were applied in the tests. The results indicate that all of the cytokinin-like regulators promote chlorphyll in a concentration of 200 ppm, the extent of promotion is, however, somewhat lower than that observed with the endogenous and synthetic cytokinins. The radiobiological test results indicate that the cytokinin-like regulators do not exert any phytotoxic effect even when applied in a concentration of 10.000 ppm.

The tests were performed on Pinto beans. The plants were treated with an endogenous cytokinin (zeatine), synthetic cytokinins (kinetin, benzyladenine) or cytokinin-like compounds, respectively, and the chlorophyll content of the leaves was determined 2 weeks after the treatment by measuring the extinction of the extract of the leaves at 665 mμ. The results, related to 200 mg fresh weight, are listed in Table 7.

                  TABLE 7                                                          ______________________________________                                         Test                                 Promotion                                 No.  Treatment        ppm    Extinction                                                                             %                                         ______________________________________                                         1    Untreated control                                                                               --     0.671   --                                        2    Zeatin           20     1.283   91.3                                      3    Kinetin          30     1.120   66.0                                      4    Benzyladenine    30     1.229   83.1                                      5    1,4-Dihydroxyphthalazine                                                                        200    0.985   46.8                                           diguanidine salt                                                          6    N--(n-Propyl)-benzimid-                                                                         200    1.081   61.2                                           azolium bromide                                                           ______________________________________                                    

EXAMPLE 18 Stimulation of the protein level of soybean

The active agent to be tested was dissolved in distilled water to form a 200 ppm solution, and soybean leaf segments, weighing 200 mg, were floated on the surface of the solution for 24 hours. In the control test leaf segments, weighing 200 mg, were floated on the surface of distilled water.

The leaf segments were washed with distilled water, and then treated for 3 hours with 20 ml of a solution containing labelled amino acid (glycine-¹⁴ C; activity: 2 μCi). After this exposition period the leaf segments were washed with an aboundant amount of water, and the protein content of the leaf segments was isolated in a manner known per se. Stock solution was prepared from the isolated protein, and the specific radioactivity of the solution was determined by liquid scintillation. The results are listed in Table 8.

                  TABLE 8                                                          ______________________________________                                         Test                  Radioactivity                                                                              Stimulation,                                 No.  Treatment        mu Ci/100 mg                                                                               %                                            ______________________________________                                         1    Untreated control                                                                               11.9        --                                           2    1,4-Dihydroxyphthalazine                                                                        16.1        35.3                                         3    1,4-Dihydroxyphthalazine                                                                        15.5        30.2                                              diguanidine salt                                                          4    N--(n-Propyl)-benzimida-                                                                        13.7        15.2                                              zolium bromide                                                            5    1:1 mixture of the active                                                                       19.6        64.7                                              agents used in Tests 3 and                                                     4                                                                         ______________________________________                                    

It appears from the data of Table 8 that, as a result of the treatments with the compositions according to the invention, the protein incorporation into soybean leaves increased by 15 to 65%.

EXAMPLE 19 Effects on protein synthesis

The stimulating effects of the compositions according to the invention exerted on protein synthesis, compared to the effects of cytokinins, are shown in Table 9. The data of Table 9 indicate that although the compositions according to the invention are less effective than the cytokinins examined, they still exert considerable stimulating effects with a tendency analogous to that of the cytokinins.

The tests were performed on leaves of Pinto bean. The leaf segments were treated with an endogeneous cytokinin (zeatin), synthetic cytokinins (kinetin, benzyladenine) or with the compositions according to the invention, respectively, by floating the leaf segments on the solution of the test substance for 18 hours. Thereafter the leaf segments were exposed to a labelled amino acid (glycine-2-¹⁴ C) for 3 hours, and the incorporation of the amino acid was determined by radiometry. The radioactivity data, expressed in units of 1000 dpm/200 mg fresh weight, are listed in Table 9.

                  TABLE 9                                                          ______________________________________                                                                  Radioactivity of the                                                                         Stim-                                                            TCA-insoluble fraction                                                                       ula-                                                             1000 dpm/200 mg fresh                                                                        tion,                                   Test Treatment    ppm    weight        %                                       ______________________________________                                         1    Untreated control                                                                           --     3.17          --                                      2    Zeatin       20     6.18          95.1                                    3    Kinetin      30     5.36          69.4                                    4    Benzyladenine                                                                               30     5.92          87.0                                    5    1,4-Dihydroxy-                                                                              200    4.40          39.0                                         phthalazine di-                                                                guanidine salt                                                            6    N--(n-Propyl)-                                                                              200    4.52          42.7                                         benzimidazolium                                                                bromide                                                                   ______________________________________                                    

EXAMPLE 20 Stimulation of the photosynthesis of plants

The compositions according to the invention were diluted with distilled water to an active agent content of 200 ppm, and leaf discs of alfalfa, soybean, bean and maize, weighing 200 mg each, were floated on the surfaces of the resulting solutions for 2 hours. Thereafter the treated leaf discs were place into the assimilation chamber of an appropriate measuring apparatus, and a known amount of radioactive carbon dioxide gas (¹⁴ CO₂) was introduced into the assimilation chamber from a reservoir by means of a gas feeder for 0.5 hours under carefully controlled illumination conditions. Thereafter the leaf discs were frozen with liquid nitrogen, triturated with 50% by weight perchloric acid in a potter homogenizer, and stock solutions were prepared from the resulting mixtures. The specific radioactivities of the stock solutions were determined by liquid scintillation.

In the control test untreated leaf discs were exposed to labelled carbon, dioxide, and the amount of carbon dioxide incorporated under such conditions was regarded as standard.

The percentage increase in the amount of incorporated labelled carbon dioxide, related to the standard, is given in Table 10.

                  TABLE 10                                                         ______________________________________                                                          Stimulation, %                                                Test                           Soy-                                            No.  Treatment         Alfalfa bean Bean Maize                                 ______________________________________                                         1    N--methyl-benzimidazolium                                                                        --      --   125  --                                         bromide                                                                   2    N--ethyl-benzimidazolium                                                                         --      --   184  --                                         bromide                                                                   3    N--bromoethyl-benzimid-                                                                          --      --   57   --                                         azolium bromide                                                           4    N--(n-propyl)-benzimid-                                                                          12      236  --   84                                         azolium bromide                                                           5    N--(n-butyl)-benzimid-                                                                           --      --   41   47                                         azolium bromide                                                           6    1,4-Dihydroxyphthalazine                                                                         --       67   4   12                                         diguanidine salt                                                          7    1:1 mixture of the active                                                                        --      --   41   47                                         agents used in Tests 4 and 6                                              ______________________________________                                    

It appears from the data of Table 10 that all of the compositions according to the invention stimulate the carbon dioxide incorporation of plants. The actual value of stimulation varies within wide limits, but the degree of stimulation is significant in most of the cases examined.

EXAMPLE 21 Stimulation of carbon dioxide fixation

The stimulating effects of the compositions according to the invention exerted on the photosynthetic fixation of carbon dioxide, compared to the effects of endogeneous and synthetic cytokinins, are demonstrated in Table 11. The data of Table 11 indicate that zeatin ("root factor") is the most potent stimulating agent, the effects of synthetic cytokinins approach to that of zeatin, and the cytokinin-like regulators are somewhat less potent than the synthetic cytokinins.

The tests were performed on leaves of Pinto beans. The leaf segments were treated with an endogeneous cytokinin (zeatin), synthetic cytokinins (kinetin, benzyladenine) or with the compositions according to the invention, respectively, by floating the leaf segments on the solution of the test substance for 18 hours, thereafter the leaf segments were exposed to labelled carbon dioxide (activity: 100 μCi/5000 ml of ¹⁴ CO₂) for 0.5 hours. The radioactivity data, expressed in units of dpm/200 mg fresh weight, are listed in Table 11.

                                      TABLE 11                                     __________________________________________________________________________                          Radioactivity, dpm/                                                                      Stimula-                                        Test                 200 mg fresh weight                                                                      tion,                                           No. Treatment    ppm A   B  C  %                                               __________________________________________________________________________     1   Untreated control                                                                           --  2.14                                                                               0.18                                                                              2.32                                                                              --                                              2   Zeatin        20 5.12                                                                               0.46                                                                              5.58                                                                              140.8                                           3   Kinetin       30 4.15                                                                               0.37                                                                              4.52                                                                              95.2                                            4   Benzyladenine                                                                                30 4.87                                                                               0.41                                                                              5.28                                                                              128.0                                           5   1,4-Dihydroxy-phthalazine                                                                   200 3.38                                                                               0.31                                                                              3.69                                                                              59.3                                                diguanidine salt                                                           6   1,4-Dihydroxy-phthalazine                                                                   200 3.75                                                                               0.28                                                                              3.47                                                                              50.7                                                monoguanidine salt                                                         7   N--(n-Propyl)-benz-                                                                         200 3.92                                                                               0.34                                                                              4.26                                                                              84.0                                                imidazolium bromide                                                        __________________________________________________________________________      A = in the light                                                               B = in the dark                                                                C = photosynthetic                                                       

EXAMPLE 22 Stimulation of plant photolysis

The compositions according to the invention were diluted with distilled water to an active agent content of 500 ppm, and green parts of maize, weighing 200 mg, were treated with the resulting solutions for 2 hours. Thereafter the treated green plant parts were treated for one hour with 10 μCi/50 ml HTO, then the plant parts were frozen with liquid nitorgen, triturated, subjected to chromatographic separation, and the radioactivity of the isolated glycerol aldehyde was determined. The results, related to 1 mg dry weight, are listed in Table 12.

In the control test the green parts of maize were treated with distilled water only.

                  TABLE 12                                                         ______________________________________                                                                              Stimu-                                    Test                   Radioactivity lation,                                   No.   Treatment        dpm/mg dry weight                                                                            %                                         ______________________________________                                         1     N--(n-Propyl)-benzimida-                                                                        8.76           88                                             zolium bromide                                                           2     1,4-Dihydroxyphthalazine                                                                        11.42         146                                             diguanidine salt                                                         3     Untreated control                                                                               4.64          --                                        ______________________________________                                    

The data listed in Table 12 indicate that the compositions according to the invention effectively stimulated the photolysis of plants.

EXAMPLE 23 Stimulation of photolytic activity

The stimulating effects of an endogeneous cytokinin (zeatin), synthetic cytokinins (kinetin, benzyladenine) and the cytokinin-like regulators according to the invention exerted on the photolytic activity connected to the decomposition of HTO were examined on leaves of Pinto bean. The leaf discs were floated for 18 hours on solutions of the substances under examination, and then exposed to a radioactivity of 200 μCi/100 ml for one hour to effect photolysis of HTO. The radioactivity data, expressed in units of dpm/mg of glucose, are given in Table 13.

                  TABLE 13                                                         ______________________________________                                         Test                      Photolytic activity                                                                        Stimu-                                   No.  Treatment     ppm    dpm/mg of glucose                                                                          lation %                                 ______________________________________                                         1    Untreated control                                                                            --      7.64       --                                       2    Zeatin        20     15.94       108                                      3    Kinetin       30     13.96       82                                       4    Benzyladenine 30     17.21       125                                      5    1,4-Dihydroxy-                                                                               200    13.72       79                                            phthalazine diguani-                                                           dine salt                                                                 6    N--(n-Propyl)-                                                                               200    14.08       84                                            benzimidazolium                                                                bromide                                                                   ______________________________________                                    

EXAMPLE 24 Stimulation of nutrient uptake

The compositions according to the invention were diluted with distilled water to an active agent concentration of 200 ppm, and leaf segments of wheat, maize and pea, weighing 200 mg each, were treated with the solutions. Thereafter the treated green leaf segments were treated for 0.5 hours with a solution of labelled phosphate ions (radioactivity: 30 μCi/50 ml). After this exposition period the treated leaf segments and the untreated controls were processed in a manner known per se to isolate the nucleic acid fractions, and the isolated nucleic acid fractions were dissolved in 6 n ammonium hydroxide solution. Stock solutions were prepared from the resulting solutions, and the amount of labelled phosphate ions present in the stock solutions were measured by liquid scintillation. The results are summarized in Table 14.

                                      TABLE 14                                     __________________________________________________________________________                  1,4-Dihydroxyphthalazine                                                                   N--(n-Propyl)-benz-                                           Control                                                                             diguanidine salt                                                                           imidazolium bromide                                   Test    1000       Stimula-    Stimula-                                        No. Plant                                                                              cpm/g                                                                               1000 cpm/g                                                                           tion, %                                                                              1000 cpm/g                                                                           tion, %                                         __________________________________________________________________________     1   Wheat                                                                              17.4 29.3  68.5  22.8  31.0                                            2   Maize                                                                              31.2 47.0  50.6  39.3  25.9                                            3   Pea 23.3 38.4  51.7  32.7  29.2                                            __________________________________________________________________________

It appears from the results that the incorporation of labelled phosphate ions into the nucleic acid fraction increased by 26-70% upon treating the plants with the compositions according to the invention, i.e. the nutrient uptake of the plants increased.

EXAMPLE 25 Stimulation of membrane activity

Unlike endogeneous and synthetic cytokinins, the compositions according to the invention also possess membrane-active side effects. The stimulation of nitrate uptake provoked by the compositions according to the invention, which manifests in the increase of total nitrogen content and protein nitrogen content, is illustrated by the data of Table 15.

The tests were performed on Pinto bean. The plants were treated with solutions of an endogeneous cytokinin (zeatin), synthetic cytokinins and membraneactive regulators according to the invention, respectively, and the leaves of the plants were analyzed 2 weeks after the treatment. The results, compared to the data observed on the controls, are given in Table 15.

                                      TABLE 15                                     __________________________________________________________________________                                             Protein                                                                        nitrogen content                                       Total nitrogen                                                                             Protein nitrogen                                                                           in % of                                Test            % of  Stimulation                                                                          % of  Stimulation                                                                          the total                              No.                                                                               Treatment ppm                                                                               dry weight                                                                           %     dry weight                                                                           %     nitrogen content                       __________________________________________________________________________     1  Untreated -- 3.8   --    2.4   --    63                                        control                                                                     2  Zeatin    20 3.8   --    2.8   16.6  73                                     3  kinetin   30 3.8   --    2.8   16.6  73                                     4  Benzyladenine                                                                            30 3.8   --    2.8   16.6  73                                     5  1,4-Dihydroxy-                                                                           200                                                                               4.8   26.3  4.1   70.8  85                                        phthalazine di-                                                                guanidine salt                                                              6  N--(n-Propyl)-benz-                                                                      200                                                                               5.3   39.4  4.4   83.3  83                                        imidazolium                                                                    bromide                                                                     __________________________________________________________________________

EXAMPLE 26 Stimulation of the total nitrogen content and protein nitrogen content of alfalfa

Alfalfa was treated with the compositions according to the invention under large-parcel field conditions. The tests were performed in fourfold replications on parcels 1 hectare in area, each. The oily compositions according to the invention were diluted with water and then sprayed onto the test parcels either once or twice.

The parcels were sprayed first when the soil was already covered with sprouting alfalfa shoots. The second treatment, if any, was performed two weeks later. The dose applied in all of the treatments was 2 kg/ha.

The total nitrogen content and the protein nitrogen content of alfalfa, harvested from the untreated, once-treated and twice-treated parcels, was measured. The results are summarized in Table 16.

                                      TABLE 16                                     __________________________________________________________________________                 Number                                                                              Total nitrogen                                                                            Protein nitro-                                                 of   content    gen content                                        Test        treat-                                                                              % of dry                                                                            Stimulation                                                                          % of dry                                                                            Stimulation                                   No.                                                                               Treatment                                                                               ments                                                                               substance                                                                           %     substance                                                                           %                                             __________________________________________________________________________     1  Untreated                                                                               --   3.36 --    2.25 --                                               control                                                                     2  1,4-dihydroxy-                                                                          1    4.17 24    3.48 54                                               phthalazine                                                                    diguanidine                                                                    salt                                                                        3  N--(n-Propyl)-                                                                          1    3.51  4    2.48  8                                               benzimidazolium                                                                bromide  2    3.91 13    2.75 22                                            __________________________________________________________________________

It appears from the test results that, upon a single treatment, the ratio of the total nitrogen content related to the dry substance content increased by 4-14%, whereas the protein nitrogen content increased by 8-24%. At the same time, the share of protein nitrogen in the total nitrogen content increased from 67% to 70-72%, i.e. an increase of 5-9% could be attained.

Upon the effect of two treatments the total nitrogen content increased by 13-24% and the protein nitrogen content increased by 22-54%. The share of protein nitrogen in the total nitrogen content increased by 5-25%.

The effects of the compositions according to the invention exerted on the crop yield (green yield), crude protein content, protein nitrogen content and C/N ratio of alfalfa, observed under field conditions in the tests performed in 1979 at the Agricultural Combinate of Boly, Hungary, are listed in Table 17.

                  TABLE 17                                                         ______________________________________                                         Test                    Green yield Increase                                   No.  Treatment          q/ha        %                                          ______________________________________                                          1   Untreated control  120.sup.    --                                          2   1,4-Dihydroxyphthalazine di-                                                                      146.sup.++  22.3                                            guanidine salt                                                             3   N--Isopropyl-benzimidazolium                                                                      142.sup.+   18.7                                            chloride                                                                   4   2 and 3, applied together                                                                         157.sup.++  31.4                                       ______________________________________                                                                 Crude protein                                          Test                    content (% of                                                                              Increase                                   No.  Treatment          dry substance)                                                                             %                                          ______________________________________                                          5   Untreated control  21.3        --                                          6   1,4-Dihydroxyphthalazine                                                                          25.4.sup.+++                                                                               19.4                                            diguanidine salt                                                           7   N--Isopropyl-benzimidazolium                                                                      25.8.sup.+++                                                                               21.5                                            chloride                                                                   8   6 and 7, applied together                                                                         27.3.sup.++ 28.6                                       ______________________________________                                                                 P.sub.2 O.sub.5 content                                Test                    (% of dry   Increase                                   No.  Treatment          substance)  %                                          ______________________________________                                          9   Untreated control  8.3         --                                         10   1,4-Dihydroxyphthalazine                                                                          10.3.sup.+  24.6                                            diguanidine salt                                                          11   N--Isopropyl-benzimidazolium                                                                      10.9.sup.++ 31.7                                            chloride                                                                  12   10 and 11, applied together                                                                       11.4.sup.+++                                                                               38.5                                       ______________________________________                                         Test                                Decrease                                   No.  Treatment          C/N ratio   %                                          ______________________________________                                         13   Untreated control   5.31       --                                         14   1,4-Dihydroxyphthalazine                                                                          3.87.sup.++ 27.2                                            diguanidine salt                                                          15   N--Isopropyl-benzimidazolium                                                                      4.20.sup.+  21.0                                            chloride                                                                  16   14 and 15, applied together                                                                       3.45.sup.+++                                                                               35.1                                       ______________________________________                                          Remarks:                                                                       .sup.+ significance degree: 5%                                                 .sup.++ significance degree: 1%                                                .sup.+++ significance degree: 0.1%                                       

EXAMPLE 27 Stimulating effect exerted on the total nitrogen and protein nitrogen content of mixed soybean/sunflower culture

Mixed soybean/sunflower cultures, to be harvested when green, were treated with the compositions according to the invention under large-parcel field conditions. The tests were performed in fourfold replications on parcels 1 hectare in area, each. The compositions were diluted with water and sprayed onto the parcels three times, in doses of 2 kg/ha, each. The first treatment was performed when the soil was already completely covered by green plants, the second treatment was performed two weeks later, and then the third after two additional weeks. The green plants were harvested from the treated and control parcels, and the total nitrogen content and protein nitrogen content were determined. The results are summarized in Table 18.

                                      TABLE 18                                     __________________________________________________________________________                                           Protein                                                Total nitro-                                                                               Protein nit-                                                                               nitrogen content                                       gen content rogen content                                                                              in % of                                  Test          % of  Stimulation                                                                          % of  Stimulation                                                                          the total                                No.                                                                               Treatment  dry weight                                                                           %     dry weight                                                                           %     nitrogen content                         __________________________________________________________________________     1  Untreated control                                                                         2.56  --    2.27  --    65.2                                     2  1,4-Dihydroxyphthal-                                                                      3.45  34.7  3.17  39.6  94.8                                        azine diguanidine                                                              salt                                                                        3  N--(n-Propyl)-benz-                                                                       2.80   9.7  2.75  21.1  98.9                                        imidazolium bromide                                                         __________________________________________________________________________

The total nitrogen content increased by 10-35% and the protein nitrogen content by 20-40% upon the effect of the treatments. The share of protein nitrogen content in the total nitrogen content increased by 45-52%, i.e. the most significant increase was attained in this respect. This also involves that the nutrition value of the green plants increased considerably, which is of great importance with respect to animal husbandry.

EXAMPLE 28 Stimulating effect exerted on the green weight, total nitrogen content and protein nitrogen content of maize for silage

The tests were performed on parcels 200 m² in area. The compositions according to the invention were utilized as solid formulations, and were diluted with water prior to applying them onto the soil. The active agent was applied to the soil in an amount of 2 kg/ha directly before sowing. The green weight of the maize for silage, harvested from the treated and control parcels, was measured, and the dry substance content, crude protein content, real protein content, nitrogen content and carbon content of the green plants were determined. The results are summarized in Table 19.

                                      TABLE 19                                     __________________________________________________________________________                          Treatment with                                                                 1,4-dihydroxyphthalazine                                                                   N--(n-propyl)-                                Test           Untreated                                                                            diguanidine benzimidazolium                               No.                                                                               Examined parameter                                                                         control                                                                              salt        bromide                                       __________________________________________________________________________     1  Green weight, kg                                                                           365   374         389                                           2  Air-dry substance,                                                                         20.57 22.79.sup.++                                                                               23.48                                            absolute %                                                                  3  Air-dry substance,                                                                         --    10.80       14.10                                            relative %                                                                  4  Crude proteins,                                                                            1.85  2.52.sup.+  2.25.sup.+                                       absolute %                                                                  5  Crude proteins,                                                                            --    36.3        21.7                                             relative %                                                                  6  Real protein content,                                                                      1.35  1.71        1.4                                              absolute %                                                                  7  Real protein content,                                                                      --    26.7        4.4                                              relative %                                                                  8  Total carbon content,                                                                      8.99  9.99.sup.++ 10.27.sup.++                                     absolute %                                                                  9  Total nitrogen content,                                                                    0.30  0.40.sup.+  0.86.sup.+                                       absolute %                                                                  10 Carbon/nitrogen ratio                                                                      30.86 25.27       28.67                                         __________________________________________________________________________      Remarks:                                                                       .sup.+ significance degree: 5%                                                 .sup.++ significance degree: 1%                                                .sup.+++ significance degree: 0.1%                                       

It appears from the data of Table 19 that, upon the effect of the treatment the green weight increased by 2-10%, the dry substance content increased by 10-15%, the crude protein content increased by 20-36%, and the real protein content increased by 4-27%, respectively. As a very favorable result, the carbon/nitrogen ratio decreased by 7-18%.

The effects of the cytokinin-like regulators on the crop yield, crude protein content and real protein content of maize for silage, observed under field conditions in the tests performed in 1979 at the Agricultural Combinate of Boly, Hungary, are listed in Table 20.

                  TABLE 20                                                         ______________________________________                                         Test                    Green weight                                                                               Increase                                   No.  Treatment          q/ha        %                                          ______________________________________                                          1   Untreated control  310.2       --                                          2   1,4-Dihydroxyphthalazine                                                                          361.3.sup.++                                                                               15.5                                            diguanidine salt                                                           3   N--Isopropyl-benzimidazolium                                                                      398.2.sup.+++                                                                              28.4                                            chloride                                                                   4   2 and 3, applied together                                                                         420.9.sup.+++                                                                              35.7                                       ______________________________________                                                                 Crude protein                                          Test                    content (% of                                                                              Increase                                   No.  Treatment          dry substance)                                                                             %                                          ______________________________________                                          5   Untreated control  13.2        --                                          6   1,4-Dihydroxyphthalazine                                                                          16.0.sup.++ 21.3                                            diguanidine salt                                                           7   N--Isopropyl-benzimidazolium                                                                      17.1.sup.++ 29.7                                            chloride                                                                   8   6 and 7, applied together                                                                         17.9.sup.+++                                                                               35.7                                       ______________________________________                                                                 P.sub.2 O.sub.5 content                                Test                    (% of dry   Increase                                   No.  Treatment          substance)  %                                          ______________________________________                                          9   Untreated control  7.5         --                                         10   1,4-Dihydroxyphthalazine                                                                          9.5.sup.++  27.2                                            diguanidine salt                                                          11   N--Isopropyl-benzimidazolium                                                                      9.8.sup.+++ 30.8                                            chloride                                                                  12   10 and 11, applied together                                                                       10.1.sup.+++                                                                               35.6                                       ______________________________________                                         Test                                Decrease                                   No.  Treatment          C/N ratio   %                                          ______________________________________                                         13   Untreated control   31.4       --                                         14   1,4-Dihydroxyphthalazine                                                                          25.9.sup.++ 17.6                                            diguanidine salt                                                          15   N--Isopropyl-benzimidazolium                                                                      23.5.sup.+++                                                                               25.4                                            chloride                                                                  16   14 and 15, applied together                                                                       20.4.sup.+++                                                                               35.2                                       ______________________________________                                          Remarks:                                                                       .sup.+ significance degree: 5%                                                 .sup.++ significance degree: 1%                                                .sup.+++ significance degree: 0.1%                                       

EXAMPLE 29 Effect on the grain yield of maize

The compositions according to the invention were applied as seed dressing agents onto the sowing-seeds of hybrid maize in a dosis of 0.5 kg/ha. The powdery compositions were wetted with water prior to application. The stand was sprayed three times during the cultivation period: first at the four-leaves development stage with a dosis of 3 kg/ha, then prior to tasseling with a dosis of 1 kg/ha, and finally prior to pollen ripening with a dosis of 2 kg/ha. The crop was evaluated as May shelled corn. The results are listed in Table 21.

                  TABLE 21                                                         ______________________________________                                         Test                      Grain yield                                          No.   Treatment           q/ha   Increase, %                                   ______________________________________                                         1     Untreated control   132.8  --                                            2     1,4-Dihydroxyphthalazine                                                                           181.9  37.0                                                diguanidine salt                                                         3     N--(n-Propyl)-benzimidazolium                                                                      149.3  12.4                                                bromide                                                                  4     N--Isopropyl-benzimidazolium                                                                       208.5  57.1                                                chloride                                                                 5     A 1:1 mixture of the active                                                                        199.2  50.2                                                agents applied in Tests 2 and 4                                          ______________________________________                                    

It appears from the data of Table 21 that the grain yield of maize increased significantly, by 12-57%, upon the treatments performed with the compositions according to the invention.

EXAMPLE 30 Effects on the grain yield of soybean

Soybean cultures were sprayed three times with the compositions according to the invention. The active agents were applied in a dosis of 2 kg/ha, in all of the treatments. The stand was sprayed first at the beginning of flowering, then at the flowering of the apical cluster, and finally two weeks after the second treatment.

The grain yield of soybean, harvested from the treated and control parcels, was measured. The results are listed in Table 22.

                  TABLE 22                                                         ______________________________________                                         Test                      Grain yield                                                                              Increase                                   No.   Treatment           q/ha      %                                          ______________________________________                                         1     Untreated control   29.53     --                                         2     1,4-Dihydroxyphthalazine                                                                           41.22     39                                               diguanidine salt                                                         3     N--(n-Propyl)-benzimidazolium                                                                      38.67     30                                               bromide                                                                  4     A 1:1 mixture of the active                                                                        39.99     35                                               agents applied in Tests 2 and 3                                          ______________________________________                                    

As it appears from the data of Table 22, the grain yield of soybean increased by 30-40% upon the treatments performed with the compositions according to the invention.

EXAMPLE 31 Effects on the grain yield of wheat and on the total and protein nitrogen contents of the grains

Two wheat varieties, Libelulla and Mexican 226 K, were utilized in the tests performed under large-parcel field conditions. The sowing seeds were coated with the compositions of the invention according to the wet powder seed dressing technique; a dosis of 2 kg/ha was applied.

The soil was also treated with the compositions according to the invention directly before sowing. A dose of 2 kg/ha was applied.

The grain yields of the wheat varieties, harvested from the treated and control parcels, were measured, and the total nitrogen content and protein nitrogen content of the grains were determined. The results are listed in Tables 23 and 24.

                  TABLE 23                                                         ______________________________________                                         Tests performed on Libelulla wheat variety                                                            Weight of grains                                        Test                   collected from                                                                              Increase                                   No.   Treatment        100 ears, g  %                                          ______________________________________                                         1     1,4-Dihydroxyphthalazine                                                                        232.35        7                                               diguanidine salt                                                         2     N--(n-Propyl)-benzimid-                                                                         357.73       65                                               azolium bromide                                                          3     Untreated control                                                                               215.79       --                                         ______________________________________                                    

It appears from the data of Table 23 that the grain yield of Libelulla wheat variety increased somewhat upon treating the plant with a composition containing 1,4-dihydroxyphthalazine diguanidine salt, whereas the composition containing the benzimidazole derivative provoked a significantly greater increase.

                                      TABLE 24                                     __________________________________________________________________________     Tests performed on Mexican 226 K wheat variety                                                 Total nitrogen                                                                            Protein nitro-                                                      content    gen content                                         Test            % of dry                                                                            Stimulation                                                                          % of dry                                                                            Stimulation                                    No.                                                                               Treatment    substance                                                                           %     substance                                                                           %                                              __________________________________________________________________________     1  1,4-Hidydroxyphthalazine                                                                    2.81 5.6   2.07 28.5                                              diguanidine salt                                                            2  N--(n-Propyl)-benzimid-                                                                     2.15 1.0   1.74  8.0                                              azolium bromide                                                             3  Untreated control                                                                           2.12 --    1.61 --                                             __________________________________________________________________________

The data of Table 24 indicate that the total nitrogen content of the grains increased somewhat upon the treatment, and the treatment effected a significantly greater increase in protein nitrogen content. In this respect the composition containing the phthalazine derivative proved to be the more active one.

EXAMPLE 32 Effects exerted on the crop yield and sugar content of sugar beet

Glomeruli of sugar beet were treated with the compositions according to the invention (a dose corresponding to 1 kg/ha was applied), and the glomeruli were sown into large parcels. The plants emerged were sprayed twice with the compositions according to the invention, applying a dose of 2 kg/ha, each.

The sugar contents of the plants grown on the treated and control parcels were examined in August. A sugar content of 16.1% was observed with the treated plants, whereas the sugar content of the untreated controls was only 15%.

The crop yield and the sugar content were also determined after harvesting. The results are summarized in Table 25.

                                      TABLE 25                                     __________________________________________________________________________                            sugar                                                                              Sugar yield                                         Test             Crop yield                                                                           content Increase                                        No. Treatment    q/ha  %   q/ha                                                                               %                                               __________________________________________________________________________     1   Untreated control                                                                           541   16.0                                                                                87.56                                                                             --                                              2   1,4-Dihydroxyphthalazine                                                                    608   16.45                                                                              100.01                                                                             14                                                  diguanidine salt                                                           3   N--(n-Propyl)-benzimid-                                                                     877   17.05                                                                              149.49                                                                             70                                                  azolium bromide                                                            __________________________________________________________________________

It appears from the data of Table 25 that the sugar yield per hectare increased significantly upon treating the plants with the compositions according to the invention. The composition containing a benzimidazole derivative proved to be particularly effective.

EXAMPLE 33 Effects exerted on the berry yield and sugar content of vine

Vine stands were sprayed with the compositions according to the invention to examine their effects exerted on the berry yield and sugar content. The compositions, diluted with water, were sprayed three times onto the plants. The first treatment was performed prior to flowering, the second one three weeks later, and the third one six weeks after the first one. The dose applied was 2 kg/ha in each of the treatments.

Comparative tests were also performed with commonly used growth regulating compositions, i.e. CCC (chlorocholine chloride), Ethrel (or Etefon; 2-chloroethylphosphonic acid) and Nevirol (N-phenyl-phthalaiminic acid). The results were compared to those observed with the untreated controls.

Two vine varieties, Pannonia and Egri leanyka, were involved in the tests. The results are given in Tables 27 and 28.

                                      TABLE 26                                     __________________________________________________________________________     Tests performed on Pannonia vine variety                                                      Berry                                                                              Sugar content                                                                           Sugar yield                                        Test           yield   Increase                                                                               Increase                                        No. Treatment  q/ha                                                                               %   %    q/ha                                                                              %                                               __________________________________________________________________________     1   Untreated control                                                                         216 13.0                                                                               --   28.08                                                                             --                                              2   1,4-Dihydroxy-                                                                            232 20.0                                                                               53.8 46.40                                                                             62                                                  phthalazine di-                                                                guanidine salt                                                             3   N--(n-Propyl)-benz-                                                                       226 15.8                                                                               21.5 35.70                                                                             27                                                  imidazolium bromide                                                        4   CCC        175 16.0                                                                               23.0 28.0                                                                              --                                              5   Ethrel     194 14.0                                                                                7.5 27.2                                                                              --                                              6   Nevirol    238 15.4                                                                               18.4 36.52                                                                             30                                              __________________________________________________________________________

                                      TABLE 27                                     __________________________________________________________________________     Tests performed on Egri leanyka vine variety                                                Berry yield     Sugar yield                                       Test             Increase                                                                            Sugar content                                                                            Increase                                       No.                                                                               Treatment q/ha                                                                               %    %      q/ha                                                                              %                                              __________________________________________________________________________     1  Untreated control                                                                        151.15                                                                             --   16.7   18.93                                                                             --                                             2  1,4-Dihydroxy-                                                                           124.23                                                                             --   16.8   15.65                                                                             --                                                phthalazine di-                                                                guanidine salt                                                              3  N--(n-Propyl)-benz-                                                                      176.92                                                                             17.0 16.7   22.16                                                                             17.0                                              imidazolium                                                                    bromide                                                                     4  CCC       144.61                                                                             --   17.0   18.44                                                                             --                                             5  Ethrel    164.61                                                                              8.9 15.7   19.38                                                                              2.3                                           6  Nevirol   169.22                                                                             11.9 16.4   20.81                                                                              9.9                                           __________________________________________________________________________

The results of the above tests indicate that the compositions exert specific effects on the individual vine varieties. The composition containing a phthalazine derivative of the formula (I) significantly increased the berry yield and sugar content, consequently the sugar yield as well, on Pannonia vine variety, whereas no such effects could be observed on Egri leanyka vine variety. On the other hand, the composition containing N-(n-propyl)-benzimidazolium bromide effected an increase in crop yield, sugar content and sugar yield on Pannonia vine variety, whereas on Egri leanyka vine variety it did not influence the sugar content, but increased the crop yield by 17%.

EXAMPLE 34 Effects exerted on the crop yield and protein nitrogen content of grass stand

Tests were performed on grass stands to examine how the compositions according to the invention influence the crop yield, furthermore the total nitrogen content and protein nitrogen content of the crop.

Parcels, 4 m² in area, were separated and pegged out on a grass land, and the parcels were sprayed three times with the compositions according to the invention. The liquid compositions were diluted with water prior to spraying, and spraying was repeated in every two weeks. A dose of 2 kg/ha w was applied in each of the treatments.

Thereafter the grass was mowed, the green crop was weighed, and the total nitrogen content and protein nitrogen content of the mowed grass were determined. The results are listed in Table 28.

                                      TABLE 28                                     __________________________________________________________________________                          Total nitrogen                                                                         Protein nit-                                                           content rogen content                                     Test                    Increase                                                                               Increase                                       No. Treatment  Crop yield                                                                           %  %    %  %                                              __________________________________________________________________________     1   Untreated control                                                                         5.10  4.22                                                                              --   2.80                                                                              --                                             2   1,4-Dihydroxyphthal-                                                                      5.35  3.89                                                                              --   2.62                                                                              --                                                 azine diguanidine                                                              salt                                                                       3   N--(n-Propyl)-benz-                                                                       5.27  5.36                                                                              27.0 3.54                                                                              26.4                                               imidazolium bromide                                                        __________________________________________________________________________

EXAMPLE 35 Increase of the crop yield of edible beans

Edible beans (Superelite variety) were sprayed once or twice with the compositions according to the invention.

The date and number of treatments and the amount of dry beans harvested are listed in Table 29. From the data of Table 29 conclusions can be drawn for the correlation between the development stage of the stand at treatment and the effect of the treatment.

                                      TABLE 29                                     __________________________________________________________________________     Test        Number  Date  Crop yield                                                                           Increase                                       No.                                                                               Treatment                                                                               of the treatments                                                                            q/ha  %                                              __________________________________________________________________________     1  Untreated control                                                                       --      --    15.00 --                                             2  N--(n-Propyl)-                                                                          1       06.20.1979.                                                                          17.77 18.4                                              benzimidazolium                                                                bromide                                                                     3  N--(n-Propyl)-                                                                          1       07.06.1979.                                                                          17.03 13.5                                              benzimidazolium                                                                bromide                                                                     4  N--(n-Propyl)-                                                                          2       06.20.1979.                                                   benzimidazolium  07.06.1979.                                                                          19.52 30.1                                              bromide                                                                     5  1,4-Dihydroxy-                                                                          1       07.06.1979.                                                                          17.77 18.4                                              phthalazine di-                                                                guanidine salt                                                              __________________________________________________________________________

EXAMPLE 36 Comparative productive biological evaluation of some benzimidazole derivatives of the general formula (II)

The biological activities of cytokinin-like factors can be well characterized by measuring the intensity of the photosynthetic carbon dioxide fixation and the incorporation of labelled amino acids into the TCA-insoluble protein fraction.

The intensity of photosynthetic carbon dioxide fixation was determined on maize leaves, utilizing ¹⁴ CO₂, whereas the incorporation of amino acids was examined on bean leaves, utilizing glycine-2-¹⁴ C. The leaf segments were treated for 18 hours with the solution sof the N-(alkyl)-benzimidazolium bromides, and then exposed for one hour to the effect of the radioactive substances (¹⁴ CO₂ or glycine-2-¹⁴ C). The radioactivities of the treated and control leaf segments are listed in Table 30 in units of μCi/g fresh weight. The standard error of the mean values did not exceed ±7% in each of the measurements.

                  TABLE 30                                                         ______________________________________                                         Test       Fixation of .sup.14 CO.sub.2                                                                Incorporation of Gly-2-.sup.14 C                       No.  Alkyl group                                                                              μCi/g %     μCi/g %                                       ______________________________________                                         1    Untreated 5.72     --    3.52     --                                           control                                                                   2    Methyl    8.12     42    4.75     35                                      3    Ethyl     6.72     18    4.25     21                                      4    Bromoethyl                                                                               6.46     13    4.36     24                                      5    n-Propyl  10.52    84    4.96     41                                      6    Isopropyl*                                                                               10.92    92    4.85     35                                      7    n-Butyl   7.49     31    4.57     30                                      ______________________________________                                          *Chloride salt                                                           

EXAMPLE 37 Stimulation of carbon dioxide fixation

The method described in Example 21 was applied to determine how the various R₁ -substituted 1,4-dihydrophthalazine diguanidine salts listed in Table 31 influence the intensity of the photosynthetic carbon dioxide fixation. The tests were performed on Pinto beans, utilizing 200 ppm of active agent, each. The fixation of labelled carbon dioxide (¹⁴ CO₂) was characterized by measuring the radioactivity of the leaf segments. The radioactivities of the leaf segments, expressed in units of dpm/200 mg fresh weight, and the percentage increases are listed in Table 31.

                  TABLE 31                                                         ______________________________________                                         Test                  Intensity of CO.sub.2 fixation                           No.     R.sub.1       dpm     Increase, %                                      ______________________________________                                         1       Untreated control                                                                            2.32    --                                               2       Methyl        3.50    50.1                                             3       Ethyl         3.58    54.3                                             4       Isopropyl     3.53    52.1                                             5       Hydroxyethyl  3.49    50.4                                             6       Chloroethyl   3.51    50.2                                             7       Allyl         3.50    50.1                                             8       Chloro        3.72    60.3                                             9       Bromo         3.65    57.3                                             10      Mercapto      3.60    55.2                                             11      Hydroxy       3.64    56.8                                             12      Methylmercapto                                                                               3.56    53.4                                             13      Methoxy       3.48    50.0                                             14      Amino         3.27    40.9                                             15      Methylamino   3.30    42.2                                             ______________________________________                                    

EXAMPLE 38 Stimulation of carbon dioxide fixation

The effects of various R₁ -substituted N-(n-propyl)benzimidazolium bromides exerted on the photosynthetic fixation of ¹⁴ CO₂ were examined as described in Example 37. The results are listed in Table 32.

                  TABLE 32                                                         ______________________________________                                         Test                  Intensity of CO.sub.2 fixation                           No.     R.sub.1       dpm     Increase, %                                      ______________________________________                                          1      Untreated control                                                                            2.32    --                                                2      Methyl        4.26    84.0                                              3      Ethyl         4.13    78.0                                              4      n-Propyl      4.22    81.0                                              5      Isopropyl     4.30    85.3                                              6      n-Butyl       4.20    81.0                                              7      Hydroxyethyl  4.10    76.7                                              8      Chloroethyl   4.00    72.4                                              9      Allyl         4.15    78.8                                             10      Chloro        4.20    81.0                                             11      Bromo         4.10    76.7                                             12      Mercapto      4.32    86.2                                             13      Hydroxy       4.16    79.3                                             14      Methylmercapto                                                                               4.00    72.4                                             15      Methoxy       4.09    76.2                                             16      Amino         3.37    45.2                                             17      Methylamino   3.84    65.0                                             18      Dimethylamino 3.76    62.0                                             ______________________________________                                    

EXAMPLE 39 Effects on the total nitrogen content and protein nitrogen content of soybean

The effects of 1,4-dihydroxyphthalazine and salts thereof exerted on the total nitrogen content and protein nitrogen content of soybean were examined as described in Example 27. The plants were sprayed with the compositions according to the invention at the beginning of the flowering of the apical cluster. The results are listed in Table 33.

                                      TABLE 33                                     __________________________________________________________________________                      Total nitrogen                                                                           Protein nitrogen                                                     content   content                                             Test             % of dry                                                                            Increase                                                                            % of dry                                                                            Increase                                       No. Treatment    substance                                                                           %    substance                                                                           %                                              __________________________________________________________________________     1   Untreated control                                                                           2.6  --   1.9  --                                             2   1,4-Dihydroxyphthalazine                                                                    4.6  77.0 3.8  100.0                                          3   1,4-Dihydroxyphthalazine                                                                    4.7  81.0 3.9  105.3                                              diguanidine salt                                                           4   1,4-Dihydroxyphthalazine                                                                    3.7  42.4 3.1   63.2                                              hydrazine salt                                                             5   1,4-Dihydroxyphthalazine                                                                    3.9  50.0 3.6   89.5                                              dihydrazine salt                                                           __________________________________________________________________________

The test results listed in Examples 13 to 39 prove that the vegetative and generative biological processes of plants can be influenced effectively with the compositions according to the invention. The treatments result not only in an increase of crop yield, but in most of the cases the quality (composition, nutrient content, nutrient value etc.) of the crop can also be influenced favorably, which represents a significant technical progress. 

What we claim is:
 1. An agricultural method for increasing the crop yield of a cultivated plant and for improving the quality thereof which comprises the step of treating the cultivated plant, its seeds or its surroundings, with an effective amount of a composition which contains 0.5 to 70% by weight of a mixture of 1,4-dihydroxy-phthalazine-diguanidine and N-(n-propyl)-benzimidazolium bromide together with 30 to 80% by weight of an inert liquid diluent, 1 to 20% by weight of a solid inert carrier, and 1 to 15% by weight of a surfactant.
 2. An agricultural method for increasing plant productivity, protein nitrogen level, and anion uptake which comprises the step of applying to a plant an effective amount of a composition which comprises 0.5 to 90% by weight of a mixture of a phthalazine of the formula (I) ##STR9## wherein B₁ and B₂ are each guanidine, and an imidazole of the formula (II) ##STR10## wherein R₂ is a straight chain or branched chain C₁ to C₅ alkyl group, and X is an organic or inorganic anion, wherein the phthalazine and the imidazole are present in a ratio of 4:1 to 1:4 by weight, together with 10 to 95% by weight of an inert solid or liquid carrier, and 1 to 10% by weight of a surfactant.
 3. The method defined in claim 2 wherein the composition is applied directly to the cultivated plant prior to sowing or planting.
 4. The method defined in claim 2 wherein the composition is sprayed onto the soil after sowing or planting.
 5. The method defined in claim 2 wherein the composition is applied to the plant in a dose between 0.5 and 20 kg/ha.
 6. The method defined in claim 2 wherein the composition is applied to the plant in a dose between 0.5 and 2 kg/ha. 